1. Field of the Invention
The present invention relates to electrical switching apparatus, such as, for example, circuit breakers and, more particularly, to circuit breakers including a molded case. The invention also relates to housings for electrical switching apparatus.
2. Background Information
Circuit breakers, such as molded case circuit breakers, include at least one pair of separable contacts. For example, a first contact is fixed within the molded case housing and a second movable contact is coupled to an operating mechanism. These separable contacts are in electrical communication with either the line or the load coupled to the circuit breaker. The operating mechanism moves the movable contact between a first, open position wherein the movable contact is spaced from the fixed contact, and a second, closed position wherein the fixed and movable contacts are in contact and electrical communication. The operating mechanism may be operated manually or by a trip mechanism.
The exterior case and, in particular, the back line end wall of the case, of molded case circuit breakers has typically been a weak link for case strength and a limiting factor in increasing the interrupting ratings of circuit breakers. Typically, the bases and covers of molded case circuit breaker housings are made of glass polyester or phenolic and are relatively very intricate. Hence, it is believed that it is not possible or practical to employ a relatively high strength and a relatively highly reinforced case material (e.g., epoxy resin glass filled; vinylester) due to the relatively poor flow characteristics and relatively high viscosity of that material.
There is room for improvement in electrical switching apparatus, such as circuit breakers, and in housings for such apparatus.